The government is still looking for two Metropark Hotel guests who disappeared after the quarantine was imposed last week and failed to come forward. Another guest was finally located at the airport yesterday when returning to the city.

Secretary for Food and Health York Chow Yat-ngok said immigration officers took the guest to Princess Margaret Hospital for quarantine.

'We do not know where the guest went to. As for the person's condition, we have to do a check-up first,' he said.

A government source revealed that the guest was a Brazilian Chinese who flew from Hong Kong to Japan and returned yesterday.

Asked how the guest had managed to leave the city without being stopped by immigration officers, who had been handed a list of missing guests, Thomas Tsang Ho-fai, controller of the Centre for Health Protection, said there might have been a 'time lag'.

'We had to go to the hotel to get the names of the guests and check who were not staying inside before giving the names to immigration,' he said, without saying when the list was sent to immigration officers.

Dr Tsang denied there was a loophole in tracing potential carriers of the virus. 'I think in major quarantine actions, very often there are some people who might not be traced. The most important action is that we gather the information as quickly as possible so these people can be quarantined in certain locations.'

On the two missing guests, Dr Chow said the government had information and was looking for them, but did not say if arrest warrants would be issued.

'We will seek legal advice to see if we need to do it. Also, we need to consider a number of health aspects to see if there is the need,' he said, adding that according to Immigration Department information, the two were still in Hong Kong.

Dr Tsang said that if the missing guests were found now and showed no symptoms, there was no point putting them in quarantine, but they must have a health check before leaving the city.

The government said earlier that it was preparing to get tough with the missing guests. They would be stopped if they tried to leave and might face legal action.